Fog, phenolic acids and UV-A light irradiation: a new antimicrobial treatment for decontamination of fresh produce

This study evaluates synergistic interactions of food grade phenolic acids (gallic and ferulic acid) and UV-A light to achieve decontamination of fresh produce using a fog to improve dispersion of the phenolic acids on produce surface. Nonvirulent strains of Escherichia coli O157:H7 and Listeria innocua were used as model bacteria and spinach was selected as a model fresh produce. Synergistic combination of a fog deposited phenolic acid and a UV-A light treatment achieved reduction in bacterial plate count up to 2 log CFU/cm2 independently of the initial load of the bacteria (104 or 106 CFU/cm2). Following the treatment, fog deposited gallic and ferulic acid could be easily removed from the surface of produce by immersion in water and the treatment did not significantly alter the total endogenous phenolic content of spinach. The treatment also did not affect the texture, but impacted the color of the spinach leaves on a Hunter's Lab scale although the visual color changes were small. Overall, this technology may aid in developing alternative approaches for decontamination processes using food grade compounds.